Pyrolysis-Gas Chromatographic Analysis of Automobile Paints

The problem facing the forensic scientist in the examination of paint as physical evidence is the limited amount of information that can be obtained from trace samples. Examination of the paint involves tests to determine the composition of the binder. These tests include spot tests which differentiate between binders by solubility and color reactions [1] and infrared spectroscopy which identifies the functional groups present in the sample [2]. Pyrolysis-gas chromatography can also be used to compare paint traces with the suspected source or, by reference to standard chromatograms, to identify the type of binder. In addition, the identity of the manufacturer of the paint smear and, in many cases, the make of automobile as well as the year, can be determined by the pyrolysis of small paint samples.